1. Field of the Invention
The invention relates to method and apparatus for recycling battery packs, and particularly to method and apparatus capable of safely recycling battery packs without waiting until the battery packs are naturally discharged.
2. Description of the Related Art
Generally, a battery pack 300 includes a battery assembly composed of a plurality of (e.g., 10 pieces of) battery modules 94 that are connected in series, as shown in FIG. 8 by way of example. Each of the battery modules 94 has a plurality of (e.g., about 6 to 8 pieces of) battery cells (which will be also called “unit cells”) of secondary batteries, such as nickel-metal hydride batteries or lithium-ion batteries, which are connected in series. The battery pack 300 further includes a control device 95 for controlling the battery assembly by monitoring charged or discharged conditions (or the states of charge) of the individual battery modules 94 and the battery modules 94 as a whole, relays for cutting off electric circuits and a safety plug 96 for mechanically cutting off circuits, a cooling blower 99 for cooling the battery assembly, and signal lines 98 and power lines 97 for connecting respective parts or components. All of these components are housed in a single case 91 that is closed by a lower plate 92, and are hermetically sealed in the lower plate 92 and the case 91. The battery pack 300 is fixed to a vehicle, for example, with connecting bolts 93 inserted through holes formed in the lower plate 92. In general, the battery pack 300 as described above is handled as an independent automobile part, and its charged portions are not exposed to the outside of the case 91.
When the battery assembly in the battery pack as describe above reaches the end of its life, the battery pack is dismantled or disassembled, and the battery assembly is separated from the other parts, so that valuable metals are recovered from the battery assembly. If the battery assembly in the battery pack is in a charged condition (which may also be called “active condition”) (normally, 200V when it is fully charged), the separating operation involves handling of voltage-carrying parts or wires.
In the meantime, Japanese Patent Application Publication No. H10-46266 (JP-A-10-46266) discloses a method for recovering metal cobalt from scrap batteries, though the disclosed method is not a method of recycling battery packs. The disclosed method includes the steps of: roasting scrap batteries of secondary batteries containing cobalt in an electrode material, at a temperature equal to or higher than 600° C., shredding and screening the roasted batteries, separating the batteries into metal scrap and ash produced by roasting, magnetically separating cobalt-containing materials from the separated ash, using a magnet, and dissolving the separated cobalt-containing materials in an acid, so as to recover metal cobalt.
Japanese Patent Application Publication No. H06-322452 (JP-A-6-322452) discloses a method for recovering valuable metals from spent lithium secondary batteries, which involves the steps of: comminuting spent lithium secondary batteries and then separating the resultant materials into magnetic substances and non-magnetic substances by first magnetic separation, roasting the obtained non-magnetic substances at 500-1000° C. under a non-oxidizing atmosphere or reducing atmosphere so as to reduce the non-magnetic substances, and further separating the resultant substances into magnetic substances and non-magnetic substances by second magnetic separation, thereby to recover valuable metals.
The recovering method as described in JP-A-6-322452 is a method of recycling spent secondary batteries as described above. In the case where a battery assembly composed of secondary cells and housed in a battery pack is to be recycled, it is still necessary to dismantle the battery pack and take the secondary cells out of the battery pack. If the battery assembly composed of the secondary cells is in a charged condition, the dismantling of the battery pack involves removal or detachment of high-voltage-carrying secondary cells, control device and wires from the battery pack, and requires workers to wear insulating protectors. Thus, it takes time and effort to accomplish the dismantling job.
Also, if the battery assembly is taken out of the battery pack after the battery assembly is discharged, for enhanced work safety, the battery pack needs to be kept in storage for a long duration of time so as to be naturally discharged, or needs to be forced to be discharged using, for example, a resistor. In these cases, the recycling operation may be prolonged or requires an additional step(s).